On Apr 22, 2007, at 4:59 AM, Aleksandr N. Sadkov wrote:
Hi all,
It seems I find out an inaccuracy in TOSSIM.
We see in tutorial (lesson11):
setNoise(node, mean, variance): Set the noise floor at node to be a
gaussian distribution with mean and variance.
That’s right according to theory (Gaussian noise)
But in TOSSIM source code we see that the noise floor has uniform
distribution:
// Pick a number a number from the uniform distribution of
// [mean-range, mean+range].
double sim_gain_sample_noise(int node) __attribute__ ((C,
spontaneous)) {
double val = noise[node].mean;
double adjust = (sim_random() % 2000000);
adjust /= 1000000.0;
adjust -= 1.0;
adjust *= noise[node].range;
return val + adjust;
}
The original plan had been to incorporate gaussian noise, but I think
it was forgotten on the wayside. The current version uses CPM
modeling, so this isn't really an issue any more.
Phil
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